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Retirement and Share-based Compensation Plans (Valuation Assumptions of Stock Options Granted to Agents) (Details) - Stock Option Plans, Independent Insurance Agent Stock Option Plans [Member]
12 Months Ended
Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Average risk-free interest rate 1.21%
Dividend yield 0.70%
Average expected life (years) 3 years 9 months
Volatility 31.20%